﻿// Copyright 2004-2011 Castle Project - http://www.castleproject.org/
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#region 导入名称空间

using System;
using System.Collections.Generic;
using System.Diagnostics;
using LightWork.DynamicProxy.Generators;
using LightWork.DynamicProxy.Generators.Emitters;

#endregion

namespace LightWork.DynamicProxy.Contributors
{
    public class InterfaceProxyTargetContributor : CompositeTypeContributor
    {
        private readonly bool canChangeTarget;
        private readonly Type proxyTargetType;

        public InterfaceProxyTargetContributor(Type proxyTargetType, bool canChangeTarget, INamingScope namingScope)
            : base(namingScope)
        {
            this.proxyTargetType = proxyTargetType;
            this.canChangeTarget = canChangeTarget;
        }

        protected override IEnumerable<MembersCollector> CollectElementsToProxyInternal(IProxyGenerationHook hook)
        {
            Debug.Assert(hook != null, "hook != null");

            foreach (var @interface in interfaces)
            {
                var item = GetCollectorForInterface(@interface);
                item.Logger = Logger;
                item.CollectMembersToProxy(hook);
                yield return item;
            }
        }

        protected virtual MembersCollector GetCollectorForInterface(Type @interface)
        {
            return new InterfaceMembersOnClassCollector(@interface, false, proxyTargetType.GetInterfaceMap(@interface));
        }

        protected override MethodGenerator GetMethodGenerator(MetaMethod method, ClassEmitter @class,
            ProxyGenerationOptions options,
            OverrideMethodDelegate overrideMethod)
        {
            if (!method.Proxyable)
                return new ForwardingMethodGenerator(method,
                    overrideMethod,
                    (c, m) => c.GetField("__target"));

            var invocation = GetInvocationType(method, @class, options);

            return new MethodWithInvocationGenerator(method,
                @class.GetField("__interceptors"),
                invocation,
                (c, m) => c.GetField("__target").ToExpression(),
                overrideMethod,
                null);
        }

        private Type GetInvocationType(MetaMethod method, ClassEmitter @class, ProxyGenerationOptions options)
        {
            var scope = @class.ModuleScope;

            Type[] invocationInterfaces;
            if (canChangeTarget)
                invocationInterfaces = new[] {typeof(IInvocation), typeof(IChangeProxyTarget)};
            else
                invocationInterfaces = new[] {typeof(IInvocation)};

            var key = new CacheKey(method.Method, CompositionInvocationTypeGenerator.BaseType, invocationInterfaces,
                null);

            // no locking required as we're already within a lock

            var invocation = scope.GetFromCache(key);
            if (invocation != null)
                return invocation;

            invocation = new CompositionInvocationTypeGenerator(method.Method.DeclaringType,
                    method,
                    method.Method,
                    canChangeTarget,
                    null)
                .Generate(@class, options, namingScope).BuildType();

            scope.RegisterInCache(key, invocation);

            return invocation;
        }
    }
}